Introduction

Thyroglossal duct cyst is the most common congenital anomaly which arises from the remnants of the thyroglossal duct and occurs in 7% of the adult population [1]. It is a fibrous cyst that forms from a persistent thyroglossal duct. The most common locations for a thyroglossal cyst are midline or slightly off midline, between the isthmus of the thyroid and the hyoid bone or just above the hyoid bone. A thyroglossal cyst can develop anywhere along a thyroglossal duct. The presentation of thyroglossal duct cyst on the tongue is quite uncommon [2] and is named Lingual Thyroglossal Duct Cyst (LTDC). Thyroglossal duct cysts most often presents with a palpable asymptomatic midline neck mass below the level of the hyoid bone. Up to half of thyroglossal cysts are not diagnosed until adult life. If left untreated, LTDC may present with life-threatening airway obstruction.

We report a case of 25 years old male with LTDC due to its rare occurrence.

Case Report

A 25 yr old young male presented with swelling in submental region (Figure 1) since 8 months. This swelling was subjected to reduce in size on pressing leading to purulent discharge from foramen caecum. There was no history of dysphagia or odynophagia.

Figure 1: Swelling in submental region.

Clinical examination

On examination there was 5 x 3 cm size swelling seen in submental region with no localised sign of inflammation. The swelling moved on protrusion of tongue and deglutination.

The swelling was soft in consistency and lead to purulent discharge from foramen caecum on pressing. There were no signs of cervical lymphadenopathy.

Patient was admitted in the ward and posted for Sistrunk’s surgery. Intra-operatively cyst was found in sublingual and submental space extending up to foramen caecum with a thick band extending to the hyoid bone. We inject the methylene blue dye in to the opening present over the foramen caecum to delineate the tract and whole cyst identified. This cyst was ligated near the foramen caecum.

Figure 3: Excision of cyst with hyoid bone and dissection of thyroglossal duct tract. A segment of hyoid bone has been removed and duct with surrounding tissue is dissected through the muscles of the tongue.

Histopathology report of the specimen was suggestive of thyroglossal duct cyst with no evidence of malignancy.

Discussion

The thyroid gland originates from the foramen cecum present in the floor of the pharyngeal gut on the 17th day of gestation. The gland then descends in front of the pharynx as a bilobed diverticulum which is initially patent. It reaches its final position in the neck by the 7th week of gestation. The duct usually disappears by the 10th week of gestation. Persistence of any portion of this duct could give rise to thyroglossal cyst. Commonly these cysts could contain thyroid tissue, hence I 131 studies should be considered in all patients with suspected ectopic thyroid. In this patient occult malignancy is more likely [3]. Rarely this could be the only functioning thyroid gland tissue.

Thyroglossal duct cysts most often present with a palpable asymptomatic midline neck mass below the level of the hyoid bone. The neck mass moves with swallowing. Some patients will have neck or throat pain, or dysphagia and the spectrum of clinical symptoms may be varied. Diagnosis is usually made clinically [4].

It has been reported that over 7% of adults have some remains of the thyroglossal duct and over 62% of them may have some ectopic thyroid tissue. Most neoplasias in the thyroglossal duct are made up of papillary carcinomas [5].

Antibiotics are indicated if infection is suspected. Definitive surgical management requires excision not only of the cyst but also of the path’s tract and branches.

Conclusion

This is a rare presentation of thyroglossal cyst in an adult patient presented with swelling in submental region.